Hi,
When I put my XJS in storage before the winter it was running smoothly. Now when I start it up it only runs on 1 bank of 6 cylinders. I replaced already cables and rotor but no result.
Any suggestions more than welcome.
Thanks

 

You have the Marelli ignition system which, in a sense, is two six-cylinder ignition systems rolled into one. It isn't unusual for one half to fail.

Since the new rotor didn't help you can swap the two coils and modules to see if the problem follows the swapping, if you get what I mean. Of course, you must begin by identifying which bank is presently dead, if you haven't already done so

Cheers
DD

 

Not directly familiar with the Marelli ignition.


But, over the years, I've developed diagnostic paths, with lots of aids. First is to separate ignition failure from fueling failure. The technique for the former has come from primitive to advanced, at least in my lexicon. Best tool. My inductance strobe timing light. Here, first apply to each coil's HT out put. If one is dark, you have it.
If both strobe, look further. Still with the strobe. Hook it to a wire on each bank, in turn, a dark isolates that bank as silent.


Thence, into the mysterious Stacked distributor. Others here can assist far better than I.


Carl

 

Hi Marmar

You say you replaced the Spark Plug Cables and Rotor but did you also replace the Distributor Cap?

Have a good look at the inside of the Old Distributor Cap and see if there are any signs of Burning or even Burn through.

Otherwise known as a 'Marelli Fire' as when only one bank of Cylinders are Firing, Raw Fuel is then being Pumped into the Exhaust Pipe of the side that is not.

When this happens, there is a potential for your Car to Catch Fire, especially if the Exhaust is hot.

This is usually caused by poor maintenance in not replacing the hard to get to Spark Plugs under the Air Con Pump.

 

To test ignition modules.

Swap the connectors between the ignition modules on the top of the radiator, also swap the input connectors to the coils, this will run the A bank on the B module and vice versa. If the problem moves then the module is your problem.

If the problem stays on the same bank put the module connectors back, leave the coil inputs swapped and swap the coil outputs (at the coil not the distributor) if the problem moves then you have a bad coil.

If the problem stays on the same bank leave the coil inputs swapped, put the coil outputs back and swap the distributor inputs, if the problem moves then the HT lead is faulty, if the problem stays on the same bank then the problem is in the distributor.

DO NOT run the engine long when you start it, just long enough to determine if the problem moves.